已知△ABC的三边BC,CA,AB的中点分别是D(﹣2,﹣3),E(3,1),F(﹣1,2),求出三个顶点的坐标及△ABC的面积.
解:设A(x,y),B(a,b),C(m,n),则a+m=-4b+
根据首字母及句意完成句子。(1)Your family name is Moore, and what's your f ____ name?(2)Can you fill in your own ID c____ ?(3)This is a boy.H ____ name is Bruce.(4)Your telephone n____ is 422-2785.(5)There are s____ days in a week.
当前世界上日益严重的环境问题主要来源于( )